When is it OK and not OK to use different types of coax between a radio and the antenna? In my station I use RG-8X between the radio and tuner, between the tuner and a bias-t for a remote switch, and from the switch to the inside of my entrance panel. From the outside of the panel to the remote switch I use LMR-400 and from the switch to the feed point is also LMR-400.

I have read that it is bad to mix coax but I have also read about people using short lengths of a different type of coax than the main feed line for jumpers in the shack. I'm just looking for clarification of when coax should definitely not be mixed and when it is OK.

You do have to be a bit more careful combining coax of differentcharacteristic impedances because you can get some impedancetransformation affects, depending on the lengths involved.Sometimes this is done intentionally, for example, a quarter waveof 75 ohm coax as an impedance matching section between a112 ohm loop and 50 ohm coax. If you just use random lengthsof 50 and 75 ohm coax you could end up with an SWR over 2 : 1,even with a 50 ohm load on the other end. But in many casesthe 75 ohm coax has lower loss, and may result in more radiatedsignal regardless of the mismatch.

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